This article is about Tertullian (c. 160 to 240 A.D.). His relation to Marcion and Montanus (Montanism) is also mentioned. His importance for apologetics, and to show that Jesus Christ is God and man, is also discussed.

This article identifies the ancient heretic Marcion as perhaps the greatest influence on today's evangelical church. The church has become practically Marcionite on account of its emphasis on the love of God to the utter ignoring of everything else, its neglect of the Old Testament, and its lack of interest in singing Psalms. The net result is and will be the worship of a God different from that of the Scriptures.

This article is about Irenaeus and his struggle against the Gnostics (Gnosticism) and against Marcion. His focus on the history of redemption is also discussed.